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United States Patent |
5,050,569
|
Beunk
,   et al.
|
September 24, 1991
|
Fuel injection system for an internal combustion engine and fuel heating
device therefor
Abstract
A fuel injection system having an air supply and a fuel injection spray
valve furnishing an air-fuel mixture to an internal combustion engine has
a fuel heating device for heating the fuel just prior to spraying from the
valve to enhance fuel-air mixing, the heater having a housing comprising a
pair of stiffly compressible housing elements clamped in sealing relation
to each other for capturing a flat ceramic heating device of positive
temperature coefficient of resistivity between the compressible housing
elements, the elements each having a central opening and a spiral groove
therein cooperating to form a chamber holding the heating device and for
guiding fuel through the grooves in heat-transfer relation to the disc
along spiral paths extending along each flat side of the heating disc, the
housing having terminals sealed therein for electrically engaging opposite
sides of the heating disc.
Inventors:
|
Beunk; Gerrit J. (Almelo, NL);
Van Den Elst; Frederik M. N. (Almelo, NL)
|
Assignee:
|
Texas Instruments Incorporated (Dallas, TX)
|
Appl. No.:
|
455487 |
Filed:
|
December 22, 1989 |
Current U.S. Class: |
123/549; 123/557; 392/479 |
Intern'l Class: |
F02M 031/00 |
Field of Search: |
123/557,549,546
219/304,305,505,299
|
References Cited
U.S. Patent Documents
1418011 | May., 1922 | Mehn | 219/305.
|
3868939 | Mar., 1975 | Friese et al.
| |
3968346 | Jul., 1976 | Cooksley | 219/305.
|
4213432 | Jul., 1980 | Levy.
| |
4235210 | Nov., 1980 | Sumiyoshi et al.
| |
4279234 | Jul., 1981 | Marcoux et al.
| |
4365746 | Dec., 1982 | Tanasawa et al.
| |
4406785 | Sep., 1983 | Siefer | 123/557.
|
4447065 | May., 1984 | Eder et al.
| |
4458655 | Jul., 1984 | Oza.
| |
4477715 | Oct., 1984 | Bell et al. | 123/557.
|
4501255 | Feb., 1985 | Van Der Ploeg et al.
| |
4508957 | Apr., 1985 | Rocchitelli | 219/305.
|
4529866 | Jul., 1985 | Leary | 123/557.
|
4633069 | Dec., 1986 | Berg et al.
| |
4898142 | Feb., 1990 | Van Wechen et al.
| |
Foreign Patent Documents |
2000670 | Jan., 1979 | GB | 219/305.
|
2145153A | Mar., 1985 | GB.
| |
Primary Examiner: Dolinar; Andrew M.
Assistant Examiner: Macy; M.
Attorney, Agent or Firm: McAndrews; James P., Haug; John A., Sharp; Melvin
Claims
We claim:
1. A fuel injection system having air supply means, a fuel injection spray
valve for selectively spraying fuel to mix with air from the air supply
means, fuel pump means furnishing fuel to the fuel injection spray valve
under pressure, and a fuel heating device for heating the fuel furnished
to the fuel injection spray valve to improve vaporizing of the fuel for
enhancing mixing of the fuel and air, the fuel heating device comprising a
heating disc of electrical resistance material, means for directing
electrical current through the heating disc for generating heat, and
housing means secured in sealing relation to the heating disc for defining
fuel flow path along at least one side of the heating disc to pass the
fuel in heat-transfer relation to the heating disc for heating the fuel,
the heating disc comprising a flat disc of ceramic material of positive
temperature coefficient of resistivity with both sides metallized, and the
housing means comprising a pair of housing elements of stiffly resilient,
compressible material secured together for forming a chamber therebetween
accommodating the heating disc therein, the housing elements having a pair
of openings extending into the chamber and having at least one spiral
groove therein pressed against a flat side of the heating disc for
defining a spiral fuel flow path over said flat disc side.
2. A fuel injection system according to claim 1 wherein each housing
element has an opening therein, has a spiral groove therein, and has one
end of its spiral groove communicating with the opening in said element,
the opposite ends of the spiral grooves in the elements being disposed at
a periphery of the chamber to communicate with each other over an edge of
the heating disc.
3. A fuel injection system according to claim 2 wherein at least one
housing element has a recess in one side thereof, has said opening therein
centrally disposed in a bottom of the recess, and has the spiral groove
therein extending from the opening to a periphery of the recess, said
heating disc being disposed in said recess.
4. A fuel injection system according to claim 3 wherein the other housing
element has a central opening therein and has the spiral groove therein
extending from the said opening to a periphery of the element along a flat
side of the element, said other element being disposed in the recess in
said first housing element with said one element side facing into the
chamber, said heating disc being disposed in said recess between said
grooves.
5. A fuel injection system according to claim 4 wherein at least one
housing element has tapered lands disposed between convolutions of the
spiral grooves therein and has distal ends of the tapered lands pressed in
sealing engagement with a flat side of the heating disc for defining said
spiral fuel flow path over the heating disc side.
6. A fuel injection system according to claim 5 having a pair of relatively
more rigid housing members disposed in surrounding relation to the pair of
housing elements, the housing members having bores communicating with said
openings in respective housing elements, and having means clamping the
housing members in assembled relation to the housing elements for
compressing the housing elements in said sealing relation and engagement
with each other and with the heating disc.
7. A fuel injection system according to claim 6 wherein the means for
directing electrical current through the heating disc comprises a pair of
terminal blade means mounted on the housing members, said housing members
being formed of electrically insulating material and having said blade
means embedded in sealing relation therein to electrically connect to the
disc and to extend from said chamber to a location exterior of the heating
device.
8. A fuel injection system according to claim 7 wherein the terminal blade
mean each comprise a terminal blade embedded in a housing member to extend
into the bore in the respective housing member, and an electrically
conductive spring means disposed in said bore and in a housing element
opening aligned therewith for electrically connecting the blade with one
side of said heating device through said bore and opening.
9. A fuel heating device for heating a fluid such as fuel comprising a
heating disc of electrical resistance material, means for directing
electrical current through the heating disc for generating heat, and a
housing means secured in sealing relation to the heating disc for defining
a spiral fluid flow path along at least one side of the heating disc to
pass the fluid in heat-transfer relation to the heating disc for heating
the fluid, the heating disc comprising a flat disc of ceramic material of
positive temperature coefficient of resistivity with both sides metallized
for heating fuel flowing in the flow path, and the housing means
comprising a pair of housing elements of stiffly resilient compressible
material secured together for forming a chamber therebetween accommodating
the flat heating disc therein, the housing elements having a pair of
openings extending into the chamber and at least one spiral groove formed
herein facing into the chamber, the housing elements being compressed in
sealing relation to each other and against opposite flat sides of the
heating disc for defining a spiral fuel flow path over at least one flat
heating disc side, each housing element having an opening therein, having
a spiral groove therein, and having one end of its spiral groove
communicating with the opening in that element, the opposite ends of the
spiral grooves in the elements being disposed at a periphery of the
chamber to communicate with each other over an edge of the heating disc,
at least one housing element having a recess in one side thereof, having
said opening therein centrally disposed in a bottom of the recess, and
having the spiral groove therein extending from the opening to a periphery
of the recess, said heating disc being disposed in said recess, the other
housing element having a central opening therein and having the spiral
groove therein extending from said opening to a periphery of the element
along a flat side of the element, said other housing element being
disposed in the recess in said first housing element with said one element
side facing into the chamber, said heating disc in said recess being
disposed between said grooves, at least one housing element having tapered
lands disposed between convolutions of the spiral grooves therein and
having distal ends of the tapered lands pressed in sealing engagement with
a flat side of the heating disc for defining said spiral fuel flow paths
over the heating disc side.
10. A fuel heating device according to claim 9 having a pair of relatively
more rigid housing members disposed in surrounding relation to the pair of
housing elements, the housing members having bores communicating with said
openings in respective housing elements, and having means clamping the
housing members in assembled relation to the housing elements for
compressing the housing elements in said sealing relation and engagement
with each other and with the heating disc.
11. A fuel heating device according to claim 10 wherein the means for
directing electrical current through the heating disc comprises a pair of
terminal blade means mounted on the housing members, said housing members
being formed of electrically insulating material and showing said blade
means embedded in sealing relation therein to electrically connect to the
disc and to extend from said chamber to a location exterior of the heating
device.
12. A fuel heating device according to claim 11 wherein the terminal blade
means each comprise a terminal blade embedded in a housing member to
extend into the bore in the respective housing member, and an electrically
conductive spring means disposed in said bore and in a housing element
opening aligned therewith for electrically connecting the blade with one
side of said heating device through said bore and opening.
Description
BACKGROUND OF THE INVENTION
The field of the invention is that of fuel injection systems for internal
combustion engines and relates more particularly to a fuel injection
system having a heater for fuel sprayed from a fuel injection spray valve.
Fuel injection systems have many advantages over carburetion systems with
respect to improving power and acceleration and the like in that sensors
can regulate fuel injection spray valves to provide the correct amount of
fuel in all circumstances and can react more quickly and accurately to
changes in throttle position to provide better engine performance.
However, fuel injection spray valves used in such systems tend to achieve
relatively poor mixing of fuel and air because air velocity and volumes
are limited and spraying action by the valves is also fairly limited in
the fuel injection process. These factors can result in poor fuel economy,
in fuel condensation in cylinder inlet passages and the like, and in
excessive emission of hydrocarbon pollutants into the atmosphere. It would
be desirable to improve fuel vaporization in such fuel injection systems
by heating the fuel but fuel heating systems which have been proposed for
that purpose have tended to be more expensive or less efficient than
desired.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide a novel and improved fuel
injection system having improved means for heating fuel being furnished to
the engine by the system; to provide an improved heater device for a fuel
injection system; and to provide such a heater device which is compact,
efficient and economical for heating fuel just prior to spraying of the
fuel from a fuel injection spray valve nozzle.
Briefly described, the novel and improved fuel injection system of the
invention comprises air supply means, a fuel injection spray including
known or any new design types having a spray nozzle and having a
regulatable spray mechanism cooperating with that nozzle for selectively
directing a measured amount of fuel such as gasoline through the nozzle,
fuel pump means for directing fuel to the spray valve under pressure, and
a fuel heating device mounted adjacent to the nozzle for heating fuel just
as it is furnished to the nozzle to be sprayed from the valve. The heating
device is adapted to provide sufficient heat to the fuel to improve
vaporization and mixing of the fuel sprayed from the nozzle, particularly
during cold weather, while avoiding such heating of the fuel as might
cause undesirable fuel vaporizing in the system prior to being sprayed
from the valve nozzle.
In accordance with this invention, the fuel heating device comprises a
housing having a pair of stiffly resilient, compressible housing elements
clamped in sealing relation to each other to form a chamber therebetween.
A flat disc of ceramic electrical resistance material of positive
temperature coefficient of resistivity (PTC) or the like is captured or
held in the chamber between the elements. The heating disc material is
selected to generate heat and to increase in temperature and resistivity
as electrical current is directed through the heating disc. Preferably the
disc material is selected to display a sharp increase in resistivity as it
is heated to a selected temperature to stabilize at a disc temperature
which is safe for avoiding fuel ignition in the heating device and for
avoiding excessive fuel vaporization in the heating device or in the spray
valve before the fuel is sprayed from the valve.
Preferably one of the noted housing elements has a recess in one side, has
an opening extending into the recess, and has a spiral groove in a bottom
of the recess extending from the opening to a side wall of the recess. The
second housing element fits snugly in the recess in the first element to
form a sealed chamber between one side of the second element and the
bottom of the noted recess. The second housing element has an opening in
the element to extend into the noted chamber and has a corresponding
spiral groove in said one side of the second housing element. The spiral
groove portions of the elements press respective opposite flat sides of
the heater disc and cooperate with the openings in the housing elements to
define a fuel flow path of significant length in heat-transfer relation to
the disc wherein the fuel is guided through spiral flow paths over
opposite sides of the flat heating disc in economical and efficient
manner.
Terminal means are mounted in the housing to electrically engage contacts
on the opposite sides of the flat heating disc through the openings in the
housing elements for electrically energizing the heating disc. Preferably
the terminal means are sealed in the housing by being embedded within
housing members. The heating device is preferably mounted on the fuel
injection spray valve to receive yield under pressure from the fuel pump
to pass such fuel through the heating device to be rapidly heated, and to
pass the heated fuel to the fuel spray valve nozzle located closely
adjacent to the heating device.
DESCRIPTION OF THE DRAWINGS
Other objects, advantages, and details of the novel and improved fuel
injection system and heating device of this invention appear in the
following detailed description of preferred embodiments of the invention,
the detailed description referring to the drawing in which:
FIG. 1 is a partial side elevation view partially in section and partially
schematic of the novel and improved and fuel injection system of the
invention;
FIG. 2 is a section view to enlarged scale along an axis of FIG. 1
illustrating the novel and improved fuel injection heating device of the
invention; and
FIGS. 3 and 4 are section views along line 3-3 and 4-4 of FIG. 2
illustrating housing elements of the heating device of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, 10 in FIG. 1 indicates the novel and improved
fuel injection system of the invention which includes an air supply means
represented schematically by the air inlet 12 of an intake manifold or the
like arranged to receive gasoline or other fuel 14 from a fuel injection
spray valve 16 to form an air-fuel mixture to be furnished to an engine
cylinder 18 through a cylinder inlet 18.1, the inlet being adapted to
receive a valve (not shown) as will be understood. The fuel injection
spray valve 16 is of a type having a small nozzle 16.1 cooperating with an
electrically operable spray mechanism indicated at 16.2. As will be
understood, the spray valve mechanism is energized through leads 20 and 22
as regulated by a control computer 24 or the like for cooperating with the
nozzle 16.1 to selectively direct and spray a measured amount of fuel
through the nozzle to be atomized or vaporized and mixed with air drawn in
through the inlet 12 to form the desired air-fuel mixture. A fuel pump
means of conventional type schematically illustrated in FIG. 1 by the fuel
inlet pipe 26 furnishes fuel to the spray valve under pressure, and a fuel
injection heating device 28 receives fuel from the fuel pump means 26 to
rapidly heat the fuel as it is furnished to the spray valve. The heating
device is electrically energized through cables 30, 32 from an automobile
power supply indicated by the line terminals 34, 36 or the like.
Preferably a relay 38 is regulated by a thermostat 40 responsive to engine
coolant temperature or the like as schematically illustrated in FIG. 1 to
permit operation of the fuel injection heating device 28 at selected times
such as under cold engine conditions or the like. In that arrangement, the
fuel injection system furnishes the proper amount of fuel to the engine
cylinder 18 in all operating conditions of the engine, and the fuel
injection heating device heats the fuel when required to assure
satisfactory fuel vaporizing as the air-fuel mixture is formed, thereby to
avoid fuel condensation in the cylinder inlet e.g. and to avoid excessive
pollution during engine operation.
In accordance with this invention, the heating device 28 as shown in FIG. 2
comprises a housing having a pair of housing elements 42, 44 of a stiffly
resilient, compressible material such as rubber or plastic. As will be
understood, such elements are formed of materials selected to be
compatible with exposure to fuel such as gasoline. The housing elements
are clamped together in sealing relation to each other to form a sealed
chamber 46 between the elements, and an electrical resistance heating disc
48 is captured or held within the chamber between the elements. Preferably
the housing element 42 has a recess 42.1 in one side, has a central
opening 42.2 in the bottom of the recess, and has a spiral groove 42.3 in
the recess bottom. The housing elements 44 fits tightly into the recess
42.1 in sealing relation to the element 42, has a central opening 44.1
extending into the chamber 46, and has a spiral groove 44.2 in one side of
the element corresponding to and facing the spiral groove 42.3 in the
chamber. See FIGS. 3 and 4. Each housing element has tapered lands 42.4,
44.3 between convolutions of the spiral grooves, and the tips of the
lands, which are preferably of small radius or somewhat pointed as shown,
are disposed in a common plane. The small radius land tips provide
improved sealing to the heating disc surface and expose more of the disc
surface for heat-transfer purposes. Each element groove communicates at
one end with the opening in the housing element and the opposite ends of
the grooves are disposed at a periphery of the chamber 46 to be in
communication with each other around an edge of the heating disc.
Preferably the housing element 42 has an integral gasket flange portion
42.5 extending around the recess 42.1.
The heating disc 48 preferably comprises a body 48.1 of a ceramic material
or the like having a positive temperature coefficient of resistivity and
has metallizations or the like forming electrical contacts on opposite
sides of the body as at 48.2, 48.3. The material of the heating disc is
selected so it self-heats when electrical current is directed through the
disc body and increases in resistance as it is heated until, at a selected
temperature, the material displays a sharp increase in resistivity for
substantially stabilizing at a disc temperature which is safe for
preventing fuel ignition or excessive fuel vaporizing as discussed below.
Preferably the heating disc is formed of a doped barium titanate material
or the like having a stabilizing temperature on the order of about
80.degree. C. to 120.degree. C.
The heating disc 48 is disposed in the chamber 46 so that the tips of the
lands 42.4, 44.3, between the spiral groove convolutions on the housing
elements are pressed in sealing engagement to respective opposite sides of
the heating disc itself to cooperate with the openings in the housing
elements to define a fuel flow path through the chamber 46 which passes
the fuel in close-heat transfer relation to the heating disc in an
economical and efficient manner. That is, the housing elements press
against the heating disc to define a fuel flow path of significant length
which extends from the central opening 42.2 along a spiral path through
the groove 42.3 over one disc side 48.2, over an edge 48.4 of the disc,
along a spiral path through the groove 44.2 over the other side of the
disc 48.3 to the central opening 44.1 in the other housing element. The
spiral fluid flow path is typically triangular in cross section as shown
but could be of variable cross section or could have baffles or other
barriers 42.6 or the like as indicated in broken lines in FIG. 3 in the
groove to add turbulence to fluid flow through the path for better
heat-transfer. A pair of housing members 50, 52 of a relatively rigid
electrical insulating material such as a plastic or ceramic material or
the like, are proportioned to fit over, and preferably to substantially
enclose, the compressible housing elements. Preferably the housing members
have interfitting portions 50.1, 52.1 for receiving the gasket flange
portion 42.5 in sealing relation therebetween. Preferably as shown the
housing member 50 has a recess receiving the housing element 42, that
housing element having its own recess 42.1 receiving the other element 44
as noted above. The housing members have reduced diameter portions 50.2,
52.2 each with a central bore 50.3, 52.3 aligned with a respective opening
in a housing element, for mating with the fuel pump means 26 and with the
fuel injection spray valve 16. The housing members are cemented, screwed,
clamped or otherwise secured in sealing relation to the pump means and to
the spray valve in any conventional manner. A housing sleeve 58 of a metal
material or the like is fitted over the larger diameter portions of the
housing members as shown in FIG. 2 and is swaged or otherwise formed
around the members as indicated at 58.1 to hold the housing members and
elements in assembled relation with the heating disc 48 so that the
elements 42, 44 are sealed together, preferably being compressed for
enhancing such sealing, and so that the housing members 50, 52 are sealed
around the elements by the integral gasket flange portion 42.5. The
holding action of the housing sleeve also serves to assure that the lands
of the housing elements between convolutions of the spiral grooves therein
are held in sealing relation to the flat sides of the heating disc.
The housing members 50, 52 mount respective terminal means 54, 56
preferably by having electrically conductive metal terminal blades 54.1,
56.1 and embedded in sealed relation within the housing member material so
that first ends 54.2, 56.2 of the blades are disposed over the central
openings 42.2, 44.1 in the respective housing elements and so that
opposite ends 54.3, 56.3 extend from the heating device through an opening
58.2 in the housing sleeve. Preferably electrically conductive spiral
metal spring means 54.4, 56.4 are positioned on, and preferably secured
to, the first ends of the terminal means to extend through the central
openings 42.2, 44.1 in the respective housing elements to electrically
engage the contacts on the opposite sides of the heating disc 48. The
terminal blades preferably have apertures 54.5, 56.5 aligned with the
bores 50.3, 52.3 in the housing members as shown in FIG. 2.
The materials of the housing elements 42, 44 are selected to have low
thermal conductivity and low thermal mass compared to the terminal means
or housing sleeve e.g. All of the components of the heating device 28 are
also small and compact so the heating device as a whole has small thermal
mass as compared to the thermal mass of the liquid fuel accommodated in
the heating device or fuel spray valve. Each of the heating device
components is of rugged construction and is adapted by their compactness
to be accommodated on the fuel spray valve closely adjacent to the
location where the fuel is sprayed from valve nozzle. In that arrangement,
when the heating device and spray valve are operated, the fuel heated in
the device is adapted to be furnished and sprayed from the valve promptly
after it is heated. Although the heating disc 48 is close to the spray
valve nozzle, the fuel is passed along a relatively long path over the
heating disc in close heat-transfer relation to the disc to be very
efficiently heated. The thermal mass of the heating device is not large as
compared to the thermal requirement for heating the fuel in the valve so
the heating device is very promptly responsive to energization of the
heating disc to transfer heat to the fuel or not as desired and is able to
transfer substantial amounts of heat to the fuel when required just before
it is sprayed to greatly enhance vaporizing and mixing of the fuel with
air just as it is fed to the engine cylinder. The heating device is
self-regulating to operate at a safe temperature to avoid fuel ignition
and to avoid bubble formation or the like in the heating device or in the
spray valve such as might interfere with accurate fuel supply by the
valve.
It should be understood that although the heating device 28 is proposed for
fuel heating it could also be used for other fluid heating within the
scope of the invention.
It should be understood that although particular embodiments of the fuel
injection system and heating device of this invention have been described
by way of illustration, this invention includes all modifications and
equivalents of the disclosed system and device falling with the scope of
the appended claims.
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